Intermittent mandatory ventilation (IMV) is the standard mode of ventilatory support in the Newborn Intensive Care Unit (NICU). IMV often results in asynchrony between an infant's spontaneous breaths and mechanical breaths delivered by the ventilator. The asynchrony may lead to thoracic air leaks, inefficient gas exchange, and disturbances in cerebral perfusion. Various reports have described the use of patient-triggered or flow-synchronized ventilation (FSV) in neonates as small as 480 g. No study has yet reported experience with a significant number of infants less than 1000 g who require longer courses of ventilatory support and are at the greatest risk for complications. In particular, these infants' tendency toward barotrauma and bronchopulmonary dysplasia, plus the high incidence of neural development sequelae, make FSV an important potential alternative to IMV. This protocol randomizes all infants less than 29 weeks of gestational age who are admitted to the NICU to either conventional IMV or to pressure-limited FSV with a ventilatory set in the "Assist/Control" mode. Thirty-two patients have been enrolled to date, sixteen in the FSV group and 16 in the IMV cohort. Analysis of the data will be performed following recruitment of eight more subjects in each group in order to obtain sufficient power for preliminary analysis.